The present invention concerns a rotor for a turbine device of a type disclosed in the PCT Publication W/O 81/01443 and Canadian Patent 1,236,030. Such a prior art device comprises:                a base;        a frame pivotably connected to the base;        a rotor comprising a pair of elongated flightings having an outer and an inner edge and a curved, e.g., semicircular, cross-section and arranged in axial direction about a geometrical axis in a symmetrical fashion such that the concave sides of the flightings partially overlap each other, defining an axial passage between the inner edges of the flightings, the flightings being twisted in a screw-shaped manner in relation to one another;        a longitudinal connecting at least one end of the rotor to a frame in a pivotable manner; and        a plurality of elongated, generally airfoil-like ribs rigidly interconnecting, at axially spaced intervals, the outer edge of each flighting with the inner edge of the other flightings, said ribs being arranged in a substantially perpendicular relationship to the geometrical axis, and the cross-sectional of the ribs being convex in one and same direction of the geometrical axis.        
It is very important for longevity reasons that the rotor be properly balanced and that it rotate so that it does not excite the natural frequencies of the rotor. The prior art rotor described above lacks a convenient means to balance the rotor and to affect the resonant frequency of the rotor easily. Further, the prior art rotor needs means for the most cost effective construction thereof.